1. Field of the Invention
The present invention relates to an optical pickup transferring apparatus and, more particularly, to an optical pickup transferring apparatus of an optical disk drive with an improved slider which supports an optical pickup.
2. Description of the Related Art
Generally, an optical disk drive to write information on and read information from an optical disk such as a compact disk (CD) and a digital versatile disk (DVD) includes a sub-chassis assembly which has an optical pickup to emit a beam onto the optical disk and then to collect light reflected therefrom in order to write or read information.
FIG. 1 is a plan view of an example of a conventional sub-chassis assembly of an optical disk drive. FIG. 2 is a perspective view of the slider of a conventional sub-chassis assembly shown in FIG. 1.
Referring to FIG. 1, a sub-chassis assembly 100 comprises a sub-chassis 101, a turntable 110 to accommodate an optical disk 103 which is rotated by a spindle motor (not shown), an optical pickup 120 to write and read information on and from the optical disk 103, and an optical pickup transferring apparatus to rectilinearly shift the optical pickup 120 in a radial direction of the optical disk 103.
The optical pickup transferring apparatus comprises a pair of guide rails 141 and 142 to allow the optical pickup 120 to move rectilinearly in a radial direction of the optical disk 103, a lead screw 151 installed in parallel with the guide rails 141 and 142 and having an external thread 152, a driving motor 150 to rotate the lead screw 151, and a slider 160 mounted on the lead screw 151 and performing motion along the lead screw 151 in accordance with the rotation of the lead screw 151 in order to rectilinearly move the optical pickup 120 in a radial direction of the radius of the optical disk 103.
The slider 160 comprises a base 161, a support 163, a floating portion 165, and a spring 169, as shown in FIG. 2.
The base 161 is connected to the optical pickup 120. The floating portion 165, coupled to the support 163, has two protuberances 167 inserted into the external thread 152 of the lead screw 151. The support 163 is integrally coupled with the floating portion 165 which thereby supportably approaches or departs from the base 161. The spring 169 is installed between the support 163 and the floating portion 165 so as to elastically bias the floating portion 165 toward the lead screw 151 with respect to the base 161.
When the lead screw 151 is rotated by the driving motor 150, the slider 160 rectilinearly shifts the optical pickup 120 in a radial direction of the radius of the optical disk 103 by the protuberances 167 inserted into the external thread 152 of the lead screw 151.
In the conventional optical pickup transferring apparatus constructed as above, if the driving motor 150 is rotated abruptly, the floating portion 165 is drifted suddenly toward the base 161 so that the protuberances 167 may escape from the external thread 152 of the lead screw 151. This effect mainly happens when the distance between the external thread 152 and the protuberances 167 becomes wider over time because of wear. Such a result may be further aggravated when the elasticity of the spring 169 weakens.
When the protuberances 167 of the slider 160 escape from the external thread 152, the slider 160 slips on the lead screw 151, which causes difficulty in configuring the firmware contained in the optical disk drive to accurately control the position and intensity of a laser beam to write and read information on and from the optical disk 103. If the strength of the spring 169 is reinforced, the protuberances 167 may be prevented from escaping from the external thread 152. However, this increases the friction between the external thread 152 and the protuberances 167 thereby causing the lead screw 151 to not rotate smoothly.
In addition to the fact that the optical pickup 120 is difficult to accurately control, the spring 169 simply pushes the floating portion 165 toward the lead screw 151 and thereby causes the protuberances 167 to be inserted into the external thread 151. Therefore, accounting of the contact load between the protuberances 167 and the external thread 152 during the servo control of the optical disk drive is difficult.